As pullulan products, “PULLULAN PF-10™” with an average molecular weight of 100,000 and “PULLULAN PF-20™” with an average molecular weight 200,000 are now commercialized by Hayashibara Shoji Co., Ltd., Okayama, Japan.
Pullulan is used in various fields such as food products, pharmaceuticals, and cosmetics because it is relatively acid- and alkali-stable, water-soluble, colorless, and odorless polysaccaride, and it has a satisfactory agglutination, adhessiveness, adhesion, stickiness, and membrane-forming properties. Furthermore, it can be easily processed into various forms of shaped products such as water-soluble filaments and colorless, transparent edible films, capsules, and tubes because of its shaping and spinning properties.
When films as examples of the shaped pullulan products are produced, various substances are usually dissolved in material aqueous pullulan solutions to improve the properties of the final products. For example, to improve the desired stability against humidity, especially the desired tolerance to dryness in shaping, glycerol and sugar alcohols are generally used. The present inventors examined in various ways and found that non-reducing saccharides composed of glucose units impart a higher level of stability against humidity to the shaped products than those attained by conventional glycerin and sugar alcohols as disclosed in Japanese Patent Application No. 129,118/2001.
In the case of producing shaped pullulan products using α,α-trehalose as non-reducing saccharides composed of glucose units, if only commercialized pullulan and α,α-trehalose products, which are usually available in a powder form, can be mixed and dissolved in appropriate solvents, the processibility would be greatly improved in actual use. However, it was revealed that such pullulan products and α,α-trehalose products would not be suitable as materials for producing shaped products because, even if they are well dispersed and mixed together, they become to be separated each other and could not keep the uniformity as a mixture of powders when received vibration during weighing, packaging, moving/transporting, and handling due to their great difference in bulk density, though they retain their powdery forms. For this reason, both the pullulan and α,α-trehalose products must be weighed each and dissolved in appropriate solvents just before use, and this hinders their handlings.
Referring to conventional pullulan products per se, they do not necessarily have a sufficient rate of water dissolution. If a greater rate of water dissolution can be imparted to such pullulan products without lowering their resistance to humidity, the workability for dissolution would be more improved.
The first object of the present invention is to provide a pullulan-containing powder that constantly retains its uniformity, does not lose its resistance to humidity, and has an improved rate of water dissolution. The second object of the present invention is to provide a process for producing the pullulan-containing powder. Further, the third object of the present invention is to provide uses of the pullulan-containing powder prepared by the process.